DIESEL FUEL COMPOSITIONS

Abstract

A diesel fuel composition comprising a first additive (i) comprising a quaternary ammonium salt and a second additive (ii) comprising a Mannich reaction product; wherein the quaternary ammonium salt additive (i) is formed by the reaction a quaternising agent which is not an ester and a compound formed by the reaction of a hydrocarbyl-substituted acylating agent and an amine of formula (B1) or (B2): wherein R.sup.2 and R.sup.3 are the same or different alkyl, alkenyl or aryl groups having from 1 to 22 carbon atoms; X is a bond or alkylene group having from 1 to 20 carbon atoms; n is from 0 to 20; m is from 1 to 5; and R.sup.4 is hydrogen or a C.sub.1 to C.sub.22 alkyl group; and wherein the Mannich reaction product additive (ii) is the product of a Mannich reaction between: (d) an aldehyde; (e) an amine; and (f) a substituted phenol; wherein the phenol is substituted with at least one branched hydrocarbyl group having a molecular weight of between 200 and 3000.

Claims

1-19. (canceled)

20. A method of inhibiting the formation of an emulsion in a diesel fuel composition, the method comprising adding to the diesel fuel a first additive (i) comprising a quaternary ammonium salt and a second additive (ii) comprising a Mannich reaction product; wherein the quaternary ammonium salt additive (i) is formed by the reaction a quaternising agent which is not an ester and a compound formed by the reaction of a hydrocarbyl-substituted acylating agent and an amine of formula (B1) or (B2): ##STR00005## wherein R.sup.2 and R.sup.3 are the same or different alkyl, alkenyl or aryl groups having from 1 to 22 carbon atoms; X is a bond or alkylene group having from 1 to 20 carbon atoms; n is from 0 to 20; m is from 1 to 5; and R.sup.4 is hydrogen or a C.sub.1 to C22 alkyl group; and wherein the Mannich reaction product additive (ii) is the product of a Mannich reaction between: (a) an aldehyde; (b) an amine; and (c) a substituted phenol; wherein the phenol is substituted with at least one branched hydrocarbyl group having a molecular weight of between 200 and 3000.

21. The method according to claim 20 wherein the quaternising agent is selected from selected from dialkyl sulfates, benzyl halides, hydrocarbyl substituted carbonates, hydrocarbyl substituted epoxides in combination with an acid, alkyl halides, alkyl sulfonates, sultones, hydrocarbyl substituted phosphates, hydrocarbyl substituted borates, alkyl nitrites, alkyl nitrates, N-oxides or mixtures thereof.

22. The method according to claim 20 wherein the quaternising agent is selected from selected from dialkyl sulfates, benzyl halides, hydrocarbyl substituted carbonates and hydrocarbyl substituted epoxides in combination with an acid.

23. The method according to claim 20 wherein the hydrocarbyl substituted acylating agent is reacted with a diamine compound of formula (B 1).

24. The method according to claim 20 wherein additive (i) is a salt of tertiary amine prepared from dimethylaminopropylamine and a polyisobutylene-substituted succinic anhydride.

25. The method according to claim 20 wherein component (a) used to prepare additive (ii) is formaldehyde.

26. The method according to claim 20 wherein component (b) used to prepare additive (ii) is a (poly)ethylene polyamine.

27. The method according to claim 20 wherein component (c) used to prepare additive (ii) is a polyisobutylene-substituted phenol.

28. The method according to claim 20 wherein in the Mannich reaction used to form additive (ii) the molar ratio of component (a) to component (b) is 2.2-1.01:1; the molar ratio of component (a) to component (c) is 1.99-1.01:1 and the molar ratio of component (b) to component (c) is 1:1.01-1.99.

29. The method according to claim 20 wherein in the reaction used to make the Mannich additive the molar ratio of component (a) to component (b) is 2-1.4:1, the molar ratio of component (a) to component (c) is 1.7-1.1:1 and the molar ratio of component (b) to component (c) is 1:1.1-1.7.

30. The method according to claim 20 wherein the diesel fuel comprises a non-renewable Fischer Tropsch fuel and/or biodiesel.

31. The method according to claim 20 wherein the diesel fuel further comprises a fuel-borne catalyst which includes a metal selected from iron, cerium, group I and group II metals, platinum, manganese and mixtures thereof.

32. The method according to claim 20 wherein the emulsion forming tendency is measured according to ASTM D7451-Water Separation Properties of Light and Middle Distillate, and Compression and Spark Ignition Fuelsor a version thereof modified as described herein.

Description

EXAMPLE 1

[0225] Additive A, a quaternary ammonium salt additive of the present invention was prepared as follows:

[0226] A mixture of succinic anhydride prepared from 1000 Mn polyisobutylene (21425 g) and diluent oilpilot 900 (3781 g) were heated with stirring to 110 C. under a nitrogen atmosphere. Dimethylaminopropylamine (DMAPA, 2314 g) was added slowly over 45 minutes maintaining batch temperature below 115 C. The reaction temperature was increased to 150 C., and held for a further 3 hours. The resulting compound is a DMAPA succinimide.

[0227] This DMAPA succinimide was heated with styrene oxide (12.5 g), acetic acid (6.25 g) and methanol (43.4 g) under reflux (approx 80 C.) with stirring for 5 hours under a nitrogen atmosphere. The mixture was purified by distillation (30 C., 1 bar) to give the styrene oxide quaternary ammonium salt as a water white distillate.

EXAMPLE 2 (COMPARATIVE)

[0228] Additive B, a Mannich reaction product additive of the prior art was prepared as follows:

[0229] A reactor was charged with dodecylphenol (170.6 g, 0.65 mol), ethylenediamine (30.1 g, 0.5 mol) and Caromax 20 (123.9 g). The mixture was heated to 95 C. and formaldehyde solution, 37 wt % (73.8 g, 0.9 mol) charged over 1 hour. The temperature was increased to 125 C. for 3 hours and water removed. In this example the molar ratio of aldehyde (a):amine (b):phenol (c) was approximately 1.8:1:1.3.

EXAMPLE 3

[0230] A polyisobutene-substituted phenol was prepared as follows:

[0231] Polyisobutene having an average molecular weight of 750 (450.3 g, 0.53 mol, 1 equiv) was heated to 45-50 C. and then phenol (150.0 g, 1.59 mol, 3 equivs) was added. The turbid mixture was stirred and boron trifluoride dietherate (15.0 g, 0.10 mol, 0.18 equivs) was added in 2-3 ml aliquots over approx two hours to provide a clear orange liquid which was stirred at 45-50 C. for 5 hours. Aqueous ammonia 35% (10.5 g, 0.22 moles) was then added and the reaction mixture stirred for 30 mins. Vacuum distillation provided 81.3 g of distillate. This was stirred at 70 C., in toluene (250.3 g) for 5 mins, before adding 250.4 g of water. The layers were separated and the toluene extract was washed twice more with water. Residual water and toluene removed under vacuum to provide the product as a viscous pale yellow liquid. (510.9 g) having a toluene content of 2 wt % and a phenol content of less than 0.2 wt %.

EXAMPLE 4

[0232] Additive C, a Mannich additive of the present invention was prepared as follows:

[0233] PIB 750 Phenol (a phenol having a polyisobutenyl substituent of average molecular weight 750) with a residual PIB content of 5 wt % (447.8 g, 425.4 g active PIB phenol, 0.50 moles, 1.3 equivs) was mixed with ethylenediamine (25.3 g, 0.38 moles, 1 equiv) and Caromax 20 solvent (225.6 g). The homogenous mixture was heated to 90-95 C. 36.7% formalin (57.12 g, 0.69 moles, 1.8 equivs) was then added over 1 hr and the reaction mixture was then held at 95 C. for 1 hr. Water was removed using a Dean-Stark apparatus. Following distillation 708.3 g of product was collected.

EXAMPLE 5

[0234] Three Diesel Additive Formulations were prepared according to Table 1

TABLE-US-00001 TABLE 1 % weight Composition 1 Composition 2 (Comparative) (Comparative) Composition 3 Additive A 57.93 28.20 28.20 Additive B 29.73 Additive C 29.73 Demulsifier/ 2.67 2.67 2.67 Dehazer(1) Antifoam (2) 1.67 1.67 1.67 Solvent (3) 37.73 37.73 37.73 Demulsifier(1) A commercially available demulsifier/dehazer comprising a mixture of phenolic resins in aromatic solvent. Antifoam (2) A commercially available antifoam additive comprising organomodified siloxanes in aromatic solvent. Solvent (3) A commercially available blend of aromatic and aliphatic solvents

EXAMPLE 6

[0235] Diesel fuel compositions were prepared by adding the additive compositions listed in table 1 to aliquots all drawn from a common batch of RF06 base fuel, and containing 1 ppm zinc (as zinc neodecanoate). In each case a total additive treat rate of 350 ppm was used.

[0236] Table 2 below shows the specification for RF06 base fuel.

TABLE-US-00002 TABLE 2 Limits Property Units Min Max Method Cetane Number 52.0 54.0 EN ISO 5165 Density at 15 C. kg/m.sup.3 833 837 EN ISO 3675 Distillation 50% v/v Point C. 245 95% v/v Point C. 345 350 FBP C. 370 Flash Point C. 55 EN 22719 Cold Filter Plugging C. 5 EN 116 Point Viscosity at 40 C. mm.sup.2/sec 2.3 3.3 EN ISO 3104 Polycyclic Aromatic % m/m 3.0 6.0 IP 391 Hydrocarbons Sulphur Content mg/kg 10 ASTM D 5453 Copper Corrosion 1 EN ISO 2160 Conradson Carbon % m/m 0.2 EN ISO 10370 Residue on 10% Dist. Residue Ash Content % m/m 0.01 EN ISO 6245 Water Content % m/m 0.02 EN ISO 12937 Neutralisation (Strong mg KOH/g 0.02 ASTM D 974 Acid) Number Oxidation Stability mg/mL 0.025 EN ISO 12205 HFRR (WSD1, 4) m 400 CEC F-06-A-96 Fatty Acid Methyl prohibited Ester

EXAMPLE 7

[0237] Diesel fuel compositions were prepared comprising the additive compositions listed in Table 1, added to aliquots all drawn from a common batch of a B7 reference fuel prepared from 93% RF06 base fuel and 7% of a biodiesel comprising rapeseed oil methyl ester. Again, a total additive treat rate of 350 ppm was used.

EXAMPLE 8

[0238] The fuel compositions prepared in examples 6 and 7 were tested using a modified version of ASTM D7451 Water Separation Properties of Light and Middle Distillate, and Compression and Spark Ignition Fuels.

[0239] This test is designed to evaluate the tendency of water and fuels to separate rather than form emulsions when they contain potential emulsion forming additives or components. In this test, 80 ml of fuel and 20 ml of water are shaken together under controlled conditions and then allowed to stand for a period of time. After 5 minutes, the volume of the aqueous layer, the fuel clarity, the fuel water separation and the interface condition are rated according to standard definitions.

[0240] The test was performed in accordance with the ASTM D7451-08 method with the exception of:

6.1) Stoppered 100 ml measuring cylinders as specified in ASTM D1094 were used instead of the tubes specified in D7451.
10.1) The aqueous phase was added to the tube first, rather than the fuel
11.1) The time taken to reach 20 ml clear water was also recorded.

[0241] Please note: the numbered sections above refer to the numbered sections of the D7451 test method.

[0242] This test is a common requirement for fuel companies when assessing fuel additive performance.

[0243] The results of the ASTM D 7451 tests in the two fuels are given in tables 3 to 6.

[0244] In these tests, the time taken for 20 ml water to return and the volume of aqueous layer at 5 minutes each give an indication of how quickly a fuel/water emulsion will separate back into two distinct phases. The interface condition rating, fuel clarity rating and fuel-water separation rating all give an indication of how well the separation has taken place

[0245] The results of duplicate ASTM D7451 tests on fuel compositions of example 6 using aqueous phases at pH4, pH7 and pH 9 are given in tables 3-5.

[0246] The results of duplicate ASTM D7451 tests on fuel compositions of example 7 using aqueous phases at pH4 are given in table 6.

TABLE-US-00003 TABLE 3 Aqueous Phase pH 7 (RF06 base fuel and 350 ppm total additive): Volume of Interface Fuel- Water T20 (Time taken Aqueous Condition Fuel Clarity Separation Additive for 20 ml of water Layer at 5 Rating at Rating at Rating at Composition to return in (mins)) mins (ml) 5 mins 5 mins 5 mins Composition 1 10:00 14 4 6 3 (Comparative) 10:00 14 4 6 3 Composition 2 4:45 20 2 6 2 (Comparative) 4:45 20 2 6 2 Composition 3 3:15 20 1b-2 6 2 3:15 20 1b-2 6 2

TABLE-US-00004 TABLE 4 Aqueous Phase pH 4 (RF06 base fuel and 350 ppm total additive): Volume of Interface Fuel- Water T20 (Time taken Aqueous Condition Fuel Clarity Separation Additive for 20 ml of water Layer at 5 Rating at Rating at Rating at Composition to return in (mins)) mins (ml) 5 mins 5 mins 5 mins Composition 1 10:00 18 3 6 2 (Comparative) 10:00 17 3 6 2 Composition 2 4:15 20 2 6 2 (Comparative) 5:30 19 2 6 2 Composition 3 2:45 20 1b 6 2 3:45 20 1b 6 2

TABLE-US-00005 TABLE 5 Aqueous Phase pH 9 (RF06 base fuel and 350 ppm total additive): Volume of Interface Fuel- Water T20 (Time taken Aqueous Condition Fuel Clarity Separation Additive for 20 ml of water Layer at 5 Rating at Rating at Rating at Composition to return in (mins)) mins (ml) 5 mins 5 mins 5 mins Composition 1 6:30 19 2 6 2 (Comparative) 9:00 17 2-3 6 2 Composition 2 4:10 20 2 6 2 (Comparative) 3:55 20 2 6 2 Composition 3 3:15 20 2 6 2 3:30 20 2 6 2

TABLE-US-00006 TABLE 6 Aqueous Phase pH 4 (B7 base fuel and 350 ppm total additive): Volume of Interface Fuel- Water T20 (Time taken Aqueous Condition Fuel Clarity Separation Additive for 20 ml of water Layer at 5 Rating at Rating at Rating at Composition to return in (mins)) mins (ml) 5 mins 5 mins 5 mins Composition 1 >30 0 4 6 3 (Comparative) >30 0 4 6 3 Composition 2 20:00 11 4 6 3 (Comparative) 20:00 10 4 6 3 Composition 3 10:00 19 2 6 2 10:30 19 2 6 2

[0247] In the above tests, Fuel Clarity and Fuel-Water Separation ratings after 5 minutes were fairly similar. However, as evidenced by the volume of the aqueous layer after 5 minutes, the interface condition rating and the time taken for 20 ml of water to return, composition 3 gave significantly better performance than compositions 1 or 2.

EXAMPLE 9

[0248] The performance of diesel fuel compositions of the present invention in modern diesel engines may be tested according to the CECF-98-08 DW 10 method.

[0249] The engine of the injector fouling test is the PSA DW10BTED4. In summary, the engine characteristics are:

Design: Four cylinders in line, overhead camshaft, turbocharged with EGR

Capacity: 1998 cm.SUP.3

[0250] Combustion chamber: Four valves, bowl in piston, wall guided direct injection

Power: 100 kW at 4000 rpm

Torque: 320 Nm at 2000 rpm

[0251] Injection system: Common rail with piezo electronically controlled 6-hole injectors.
Max, pressure: 1600 bar (1.610.sup.6 Pa). Proprietary design by SIEMENS VDO
Emissions control: Conforms with Euro IV limit values when combined with exhaust gas post-treatment system (DPF)

[0252] This engine was chosen as a design representative of the modern European high-speed direct injection diesel engine capable of conforming to present and future European emissions requirements. The common rail injection system uses a highly efficient nozzle design with rounded inlet edges and conical spray holes for optimal hydraulic flow. This type of nozzle, when combined with high fuel pressure has allowed advances to be achieved in combustion efficiency, reduced noise and reduced fuel consumption, but are sensitive to influences that can disturb the fuel flow, such as deposit formation in the spray holes. The presence of these deposits causes a significant loss of engine power and increased raw emissions.

[0253] The test is run with a future injector design representative of anticipated Euro V injector technology.

[0254] It is considered necessary to establish a reliable baseline of injector condition before beginning fouling tests, so a sixteen hour running-in schedule for the test injectors is specified, using non-fouling reference fuel.

[0255] Full details of the CEC F-98-08 test method can be obtained from the CEC. The coking cycle is summarized below.

1. A warm up cycle (12 minutes) according to the following regime:

TABLE-US-00007 Duration Engine Speed Torque Step (minutes) (rpm) (Nm) 1 2 idle <5 2 3 2000 50 3 4 3500 75 4 3 4000 100
2. 8 hrs of engine operation consisting of 8 repeats of the following cycle

TABLE-US-00008 Duration Engine Speed Load Torque Boost Air After Step (minutes) (rpm) (%) (Nm) IC ( C.) 1 2 1750 (20) 62 45 2 7 3000 (60) 173 50 3 2 1750 (20) 62 45 4 7 3500 (80) 212 50 5 2 1750 (20) 62 45 6 10 4000 100 * 50 7 2 1250 (10) 20 43 8 7 3000 100 * 50 9 2 1250 (10) 20 43 10 10 2000 100 * 50 11 2 1250 (10) 20 43 12 7 4000 100 * 50 * for expected range see CEC method CEC-F-98-08
3. Cool down to idle in 60 seconds and idle for 10 seconds
4. 4 hrs soak period

[0256] The standard CEC F-98-08 test method consists of 32 hours engine operation corresponding to 4 repeats of steps 1-3 above, and 3 repeats of step 4, i.e. 56 hours total test time excluding warm ups and cool downs.

[0257] In each case, a first 32 hour cycle was run using new injectors and RF-06 base fuel having added thereto 1 ppm Zn (as neodecanoate). This resulted in a level of power loss due to fouling of the injectors.

[0258] A second 32 hour cycle may then be run as a clean up phase. The dirty injectors from the first phase were kept in the engine and the fuel changed to RF-06 base fuel having added thereto 1 ppm Zn (as neodecanoate) and the test additives.

EXAMPLE 10

[0259] The effectiveness of the additives of the present invention in older engine types may be assessed using a standard industry testCEC test method No. CEC F-23-A-01.

[0260] This test measures injector nozzle coking using a Peugeot XUD9 A/L Engine and provides a means of discriminating between fuels of different injector nozzle coking propensity. Nozzle coking is the result of carbon deposits forming between the injector needle and the needle seat. Deposition of the carbon deposit is due to exposure of the injector needle and seat to combustion gases, potentially causing undesirable variations in engine performance.

[0261] The Peugeot XUD9 A/L engine is a 4 cylinder indirect injection Diesel engine of 1.9 litre swept volume, obtained from Peugeot Citroen Motors specifically for the CEC PF023 method.

[0262] The test engine is fitted with cleaned injectors utilising unflatted injector needles. The airflow at various needle lift positions have been measured on a flow rig prior to test. The engine is operated for a period of 10 hours under cyclic conditions.

TABLE-US-00009 Stage Time (secs) Speed (rpm) Torque (Nm) 1 30 1200 30 10 2 2 60 3000 30 50 2 3 60 1300 30 35 2 4 120 1850 30 50 2

[0263] The propensity of the fuel to promote deposit formation on the fuel injectors is determined by measuring the injector nozzle airflow again at the end of test, and comparing these values to those before test. The results are expressed in terms of percentage airflow reduction at various needle lift positions for all nozzles. The average value of the airflow reduction at 0.1 mm needle lift of all four nozzles is deemed the level of injector coking for a given fuel.

EXAMPLE 11

[0264] A diesel fuel composition was prepared by adding 350 ppm of additive composition 3 described in example 5 to a base fuel having the specification defined in example 6. This fuel and a base fuel were tested in a Peugeot XUD9 A/L Engine according to the method described in example 10. The results are shown in table 7.

TABLE-US-00010 TABLE 7 Additive Composition Treat rate, mg/kg % Flow Loss Basefuel 76.8 Composition 3 350 2.3